The frequency of advanced adenoma in consulting patients: a nationwide survey in Iceland (2003–2006)

Abstract

To assess the frequency of advanced colorectal adenomas in consulting patients in Iceland. The histological configuration of colorectal adenomas (CRA) found in 3603 patients was classified into tubular (TA), villous (VA) and serrated (SA) and the degree of neoplastic severity into low-grade dysplasia (LGD), high-grade dysplasia (HGD), carcinoma in situ (CIS), intramucosal carcinoma (IMC) and submucosal carcinoma (SMC). Advanced CRA were those showing HGD, CIS, IMC and/or SMCs. In patients with two or more adenomas, the adenoma with the highest degree of epithelial neoplasia was selected to record cases. Between 2003 and 2006 a total of 19424 endoscopic examinations (13572 colonoscopies and 5852 sigmoidoscopies) were performed in Iceland (mean, 4856 endoscopies per year). At histology a mean of 759.3 CRA per year were found. Thus, CRA were found in 15.6% of the colorectal endoscopies performed per year. Out of the 3037 CRA studied, 67% were TA, 29% VA and the remaining 4% SA. LGD was present in 79%, HGD in 15%, CIS in 2.4%, IMC in 1.9% and SMC in 1.9%. Consequently, out of 3037 CRA investigated, 652 (21.5%) were advanced CRA; 71% of these showed HGD, 11% CIS, 9% IMC and 9% SMC. Two-thirds of the 652 advanced CRA were advanced VA, and more than three-quarters of 58 advanced CRA with SMC, were advanced VA. Advanced VA displaying intraepithelial neoplasia (HGD and CIS) showed a propensity to evolve into invasive carcinoma. Accordingly, VA displaying HGD and CIS might be regarded as biological markers for predicting colorectal cancer risk. This is the first study in which the frequency of CRA and advanced CRA detected in consulting patients is reported on a nationwide basis.